How do you use parallax to measure the distance of the star?

Question

I don't know,

Do you?

Answer 1

To get an idea of what parallax is, hold your finger out in front of your eyes then close one eye then the other. You will see your finger move in front of any more distant object like another chair or wall. This is because your eyes are apart and see your finger and the background at slightly different angles. What astronomers do is the same thing with telescopes by measuring how far a star moves in relation to other stars in the background which are too far to show any parallax.

As Heinz said, astronomers usually wait 6 months between viewing the object they want to measure the parallax of. This way their telescope has moved from one half of the earth's orbit to the other half which maximizes the parallax. The more powerful telescopes that astronomers use can measure the parallax of some of the closer stars, like Alpha Centari which is only 4.3 light years away.

Answer 2

That is usually done from opposite side of the earths orbit, to get a maximum spread. But even there is a problem since even a 1 second slice only goes out to 3.261630751 light years, which is called a parsec
But the closest stars are about 4.3 light years away, which means that the measurement would be at less than 1 second of arc.

Answer 3

If one used the Hubble's High Resolution Channel (HRC) camera, whose field of view is 29 arcsecs (as) with 1024 pixels across that.
http://en.wikipedia.org/wiki/Advanced_Camera_for_Surveys

The pixel resolution would be allow detection of 0.0006 arcsec shift in parallax, since centroid position error can be measured to about 1/50 of a pixel. With a baseline of 186,000,000 miles, that would represent about 11,000 light years of distance that's resolvable.

Naturally, the uncertainty of such a measurement is gigantic, on the order of about 4000 light years.